Abstract. Software tools that analyze and generate code from ORM conceptual schemas are highly susceptible to feature interaction bugs. When testing such tools, test suites are needed that cover many combinations of features, including combinations that rarely occur in practice. Manually creating such a test suite is extremely labor-intensive, and the tester may fail to cover feasible feature combinations that are counter-intuitive or that rarely occur. This paper describes ATIG, a prototype tool for automatically generating test suites that cover diverse combinations of ORM features. ATIG makes use of combinatorial testing to optimize coverage of select feature combinations within constraints imposed by the need to keep the sizes of test suites manageable. We have applied ATIG to generate test inputs for an industrial strength ORM-to-Datalog code generator. Initial results suggest that it is useful for finding feature interaction errors in tools that operate on ORM models.